// patterns/adapt/Adapter.java

// (c)2017 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// Variations on the Adapter pattern

// {java patterns.adapt.Adapter}

package patterns.adapt;

class WhatIHave {

public void g() {}

public void h() {}

}

interface WhatIWant {

void f();

}

class ProxyAdapter implements WhatIWant {

WhatIHave whatIHave;

ProxyAdapter(WhatIHave wih) {

whatIHave = wih;

}

@Override

public void f() {

// Implement behavior using

// methods in WhatIHave:

whatIHave.g();

whatIHave.h();

}

}

class WhatIUse {

public void op(WhatIWant wiw) {

wiw.f();

}

}

// Approach 2: build adapter use into op():

class WhatIUse2 extends WhatIUse {

public void op(WhatIHave wih) {

new ProxyAdapter(wih).f();

}

}

// Approach 3: build adapter into WhatIHave:

class WhatIHave2 extends WhatIHave

implements WhatIWant {

@Override

public void f() {

g();

h();

}

}

// Approach 4: use an inner class:

class WhatIHave3 extends WhatIHave {

private class InnerAdapter implements WhatIWant{

@Override

public void f() {

g();

h();

}

}

public WhatIWant whatIWant() {

return new InnerAdapter();

}

}

public class Adapter {

public static void main(String[] args) {

WhatIUse whatIUse = new WhatIUse();

WhatIHave whatIHave = new WhatIHave();

WhatIWant adapt= new ProxyAdapter(whatIHave);

whatIUse.op(adapt);

// Approach 2:

WhatIUse2 whatIUse2 = new WhatIUse2();

whatIUse2.op(whatIHave);

// Approach 3:

WhatIHave2 whatIHave2 = new WhatIHave2();

whatIUse.op(whatIHave2);

// Approach 4:

WhatIHave3 whatIHave3 = new WhatIHave3();

whatIUse.op(whatIHave3.whatIWant());

}

}